The investigation revealed that the SUV contained a device highly fraudulent by the jury: simple alarms, a wire “bird’s nest”, eight bags of fertilizer, 10-gallon jerry cans of gasoline, M88 firecrackers, and three propane tanks. The intention was clearly to create a multi-stage explosive device that resulted in a fuel-air explosion with catastrophic force, blowing bomb and car fragments into the surroundings and killing, maiming, and causing an enormous amount of damage – pure terror, in the heart of New York. The tiny amounts of data police have revealed to the press so far indicates that the bomb partially exploded, with some M88s exploding, sending smoke from the bomb into the smart T-shirt vendor.
But could it have actually thrived? Let’s take a look at them in individual parts.
The firecrackers used are a common low-grade “toy” explosive in the United States. A quick Google reveals a wealth of web data about how it is used for fun, and how to modify it. To see how powerful a single person is, watch the video below:
The M88 has one fiftieth of the explosive content of an M80 grenade, which is illegal in the United States. The M80 has about 3 grams of explosive inside, while a stick of dynamite has about 140 grams of firework chemistry inside. This means that a single M88 has about 2,300 times less explosive power than a stick of dynamite – assuming they have the same chemistry as a bomb, which they don’t: Fireworks have a flicker-like explosive content, designed to burn very quickly with a literal and vivid flash. And there’s the issue of trying to piece the M88s together to act as a big piece of explosives – the geometry of things, surface area and so on all play a role in how they “explode”. Basically, it’s really hard to make any kind of bomb like this.
Gasoline burns well but explodes? Not much. Despite what you’ve seen in the movies, and even those horrible warnings of sparks from your cell phone and the danger of exploding at a gas station, it’s really hard for gasoline to explode – you have to get a very subtle mixture of gas and air droplets.
If you ever feel uncomfortable dealing with local gas tanks, perhaps if you are camping, you need to relax. Handle them carefully by all means, but they are not as dangerous as you might worry. To prove it, the Mythbusters attempted to recreate a scene from James Bond in which Bond shoots his 9mm car at a gas tank to generate an explosion big enough to detonate his attackers. their results? You can watch the clip at this link.
Suffice it to say that you need a surprisingly powerful round of rifle to pierce your propane tank. And then, when you do, the resulting gas leak doesn’t explode, or even turn into a deadly column of flame—even when using hot burning tracer rounds to pierce the tank. This is not a purely scientific test, but the Mythbusters team found that you need to use high explosives to penetrate the gas and detonate it inside the propane tank … burning flames from the dangerous percussive force of destructive explosions.
Fertilizer bombs are popular and have been used by terrorist organizations for years, thanks to the relative ease of access to ammonium-based fertilizers. But in reality, making a bomb out of things is not so easy, thank goodness. First you need a detonator and liquid fuel. The detonator sends a pressure wave through the compost, causing the particles to decompose and release gaseous oxygen, which is then ignited by the explosive energy of the detonator. Getting the fuel-to-fertilizer ratio is difficult, and so it is difficult to achieve a dense enough fertilizer filling that the initial blast does not disperse the rest of the fertilizer in a cloud of dust.
Put all these explosive items together and what do you have? A shocking blast, or a non-explosive flicker, some kind of failed Rob Goldberg bomb? The latter, obviously.
Times Square photo, via Newsweek
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